mashell Posts: 5, Reputation: 1 New Member #1 Mar 27, 2011, 09:53 AM
Given the set of digits{2,3,4,7,8,9} how many three-digit numbers can be formed?
Given the set of digits{2,3,4,7,8,9} how many three-digit numbers can be formed?
 Stratmando Posts: 11,188, Reputation: 508 Uber Member #2 Mar 27, 2011, 10:13 AM

Hope there is a magic Formula, that someone knows, otherwise:
You could start with 234, 237, 238, 239. 243, 247, 248, 249, 273, 274,278, 279, 283, 284, 287, 289, 293, 294, 297, and 298.
See if I missed some of the set that starts with a 2. I would think ever how many numbers is found with 2's should be able to be multiplied by 6, as each number should have the same to a starting number.
Couple of good Math Guys/Girls? Could give good input.
 galactus Posts: 2,271, Reputation: 282 Ultra Member #3 Mar 27, 2011, 10:37 AM

If repetition is allowed, then there are

$6^{3}=216$ numbers that can be formed.

If repetition is not allowed, then there are

$6\cdot 5\cdot 4=120$ numbers that can be formed.

When forming 3 digit numbers, order is important.

So, $P(6,3)=120$

Stratmando, you're on the right track. You have 20 listed that start with 2.

There are 6 digits, so 20*6=120
 Stratmando Posts: 11,188, Reputation: 508 Uber Member #4 Mar 27, 2011, 01:15 PM

Galactus, I was going to mention you, but didn't wan't to leave someone out so I mentioned no one
Hey, Cool that it works out(20 combinations X 6 = 120).
I love Math and figuring, barely made it through High School. I Love solving problems.

Galactus,
I have a couple of Locks, I lost the Keys, and when pulling the pins, I accidentally dumped them, there are 4 different pins, 2 are the same length, What are the total number of keys to be made to insure 1 of them works?

Thanks, you are ALWAYS good on this stuff. Take care.
 mashell Posts: 5, Reputation: 1 New Member #5 Mar 27, 2011, 02:56 PM
Given the set of digits{2,3,4,7,8,9} how many three-digit odd numbers can be formed
Given the set of digits{2,3,4,7,8,9} how many three-digit odd numbers can be formed
 jcaron2 Posts: 986, Reputation: 204 Senior Member #6 Mar 27, 2011, 03:01 PM
Half as many as in your previous question.

 Question Tools Search this Question Search this Question: Advanced Search

Check out some similar questions!

Square of the units digit. Find the number.

How many 4 digits number formed of only odd digits are divisible by five

Hello you guys. I am studying for the GRE... and I had found that I forgot most high school math. I remember that once sometime told me that there was a way to now if a more than two digit number was a prime, but I donīt remember it. I have already researched about it in your post but canīt find an...

Prime numbers 400-digit number [ 26 Answers ]

I need to find 2 prime numbers that, if multiplied, would generate a 400-digit number. Any idea how to go about this. I have all the prime numbers but no matter what I do I do not get 400. Am I looking at this question wrong maybe? Thanks ::confused:

9 digit zip code imports as 0, not 9 digits [ 8 Answers ]

I am using MS Word and MS Excel 2003. From MS Word, I have done a MAIL MERGE, and some of the zip codes are 5 digit, while others are 9 digit, as in 12345-6789. After doing the mail merge, and previewing the letters, the 9 digit zip codes get imported as 0. Certainly the MS Word software should...